The present invention concerns an optical fiber device for the transportation and focalization of laser radiation, particularly suited for medical, surgical and biological applications.
As is well known, laser radiation may be employed for therapeutical and surgical applications. To solve the problem of energy transference from the laser output to the biological tissue to be treated, optical fibers may be utilized in the case of Nd:YAG laser, Argon laser, He-Ne laser and similar lasers. Fibers are presently available with a very low attenuation (6-10 dB/Km) suitable for transmitting powers of some tens of watts, with negligible losses and without suffering any deterioration.
In the case of known optical fibers, with plane surface termination, the laser ray departing from the fiber has its narrowest size on the output face only, becoming wider as it moves away from it. For this reason, it is necesssary to put the end face of the fiber in direct contact with the material to be treated. Otherwise, the laser power employed has to be considerably increased.
On the other hand, if the fiber is kept in contact with the target, a system for the continuous washing or cleaning of the fiber end has to be provided, whereas if the fiber is kept separated from the target, undesired effects may be produced in the area surrounding the target; moreover, the increase of the applied power causes a notable increase in the cost of the equipment.
To eliminate such drawbacks, it has been proposed to set up a suitable optical system comprising one or more lenses arranged at a convenient distance from the plane end face of the fiber, likely to focalize the laser radiation by providing an output cone of convenient width.
This system, however, encounter difficulties with the adjustment and alignment of the fiber to the optical system, in addition to size problems, rendering it ill-adapted for use in close cavities and in microsurgery.
The aim of the present invention is to provide a laser radiation, transportation and focalization system by means of an optical fiber likely to overcome the a.m. drawbacks and, therefore, particularly convenient for medical, surgical, and biological applications.
This aim is attained, according to the invention, with an optical fiber device for the transportation and focalization of laser radiation wherein the output termination of the optical fiber presents a curved convex surface which may be spherical.
Another feature of the invention is that, in the exit termination of the optical fiber, a micro-lens may be embodied, formed from material presenting a different refraction index.
Other features and advantages of the invention will become apparent during the course of the following description.